Catalytic Activity of Tungsten-dioxo and Tungsten-diimido Complexes

<p>Due to the significant decline in the availability of petrochemical resources and the increasing demand for the useful olefin mixtures extracted from oil, a sustainable and efficient alternative to these materials has become vital. Fortunately, renewable biomass derived materials may serve as a sustainable solution to the limited resources problem. Molecules derived from the degradation of biomasses are highly oxygenated and highly functionalized. Developing processes to efficiently defunctionalize these oxygen-rich materials will lead to potential up-conversion to carbon chemicals. Homogeneous catalytic deoxygenation processes present an opportunity to access valuable carbon commodity chemicals from biomass derived polyols. This dissertation details the design, development, and synthesis of d0 dioxo-W(VI) complexes bearing a bulky phenolate ligand which were active towards the dehydration and deoxydehydration of polyols. The selective homogeneous dehydration of 1-phenyl ethanol to styrene was performed at low catalytic loading with high yields. The dehydration of a variety of other alcohols was also successful including glucose. The dioxo-W(VI) complexes were shown to be competent catalysts for the deoxydehydration (DODH) of various diol substrates exemplifying the first reported tungsten catalyzed DODH. Multiple DODH reaction mechanisms were accessible with reduction of the W-O bond achieved by oxidative C-C bond cleavage and transfer hydrogenation. The reduction of dioxo-W(VI) complexes via oxygen atom abstraction by phosphites was also shown. Diimido-tungsten complexes with pincer ligands were synthesized, characterized, and found to react through heterometathesis with a variety of substituted aldehydes to form imines and tungsten dioxo complexes. A variety of group VI metal-oxo aryloxide complexes were also synthesized and characterized.</p>

Name thesis:degree_name

Doctor of Philosophy in Chemistry (PhD)

Level thesis:degree_level

Dissertation

Year dc:date.available

2022

Author dc:creator

• DeNike, Kayla

Advisor dc:contributor.advisor

• Kilyanek, Stefan M.

Contributors dc:contributor

• Allison, Neil T.
• McIntosh, Matthias C.

• Petrochemical
• olefin mixtures
• renewable biomasses
• Environmental Chemistry
• Inorganic Chemistry
• Organic Chemistry

Repository record dc:identifier

https://scholarworks.uark.edu/etd/4584

OAI identifier oai:identifier

oai:scholarworks.uark.edu:etd-6134